Fujitani Shigeki, Yu Victor L
Infectious Disease Section, West Los Angeles Healthcare Center, VA Greater Los Angeles Healthcare System, Los Angeles, California, USA.
Clin Infect Dis. 2006 Sep 1;43 Suppl 2:S106-13. doi: 10.1086/504488.
The diagnosis of ventilator-associated pneumonia has been clouded by uncertainty, because a reference standard has never been established. The use of invasive procedures to obtain respiratory tract samples for culture, with quantitation of the bacteria isolated, has been the approach most commonly advocated. Quantitation of bacteria from lower respiratory tract specimens can be used to distinguish colonization from infection. We review the invasive procedures (bronchoalveolar lavage, protected specimen brushing, nonbronchoscopic bronchoalveolar lavage, and blinded bronchial sampling), the methods of quantitation used, the types of catheters used, the sample collection methods, and the criteria used as cutoffs for the quantitative cultures. Quantitation of lower respiratory tract samples is inherently unstable from a mathematical perspective, given the variability in the volume of fluid instilled and reaspirated and the magnitude and complexity of the area being sampled. We also briefly review the use of quantitation for bacterial infections other than pneumonia, including urinary tract infection and catheter-related bacteremia. The variability in both the methods and reference criteria in the studies reviewed show that the quantitation approach is neither standardized nor evidence based.
呼吸机相关性肺炎的诊断一直存在不确定性，因为从未确立过参考标准。采用侵入性操作获取呼吸道样本进行培养，并对分离出的细菌进行定量，是最常被提倡的方法。对下呼吸道标本中的细菌进行定量可用于区分定植与感染。我们回顾了侵入性操作（支气管肺泡灌洗、保护性标本刷检、非支气管镜下支气管肺泡灌洗和盲法支气管采样）、所使用的定量方法、所用导管类型、样本采集方法以及用作定量培养临界值的标准。从数学角度来看，鉴于所注入和回吸的液体量存在变异性以及采样区域的大小和复杂性，下呼吸道样本的定量本质上是不稳定的。我们还简要回顾了定量方法在除肺炎之外的其他细菌感染中的应用，包括尿路感染和导管相关菌血症。所回顾研究中的方法和参考标准均存在变异性，这表明定量方法既未标准化，也缺乏循证依据。
